Bottom keys are cut off

The bottom row of keys is cut off a little bit. I think this may have happened inadvertently as a result of https://source.puri.sm/Librem5/squeekboard/merge_requests/43

This image shows the problem (the red rectangles are the same size):

Of course, the keys should not be cut off, and there should be a bit of margin below them, to make it harder to accidentally click the home bar (somewhat related to https://source.puri.sm/Librem5/squeekboard/issues/36)